The battle of wits between Zhuge Liang and Sima Yi in "Six Out of Qi Mountain" is one of the most classic episodes in the history of the Three Kingdoms. However, the confrontation between the two old enemies did not start with Kong Ming's Northern Expedition, but began after Liu Bei's death. After the Battle of Yiling, Shu made matters worse, and Liu Beituo died of illness soon after, which greatly damaged the vitality of Shu. After Cao Pi ascended the throne, the old strategists of the Wei State withdrew from the court one after another, and Sima Yi emerged. Because Liu Chan had just succeeded to the throne of Shu, many ministers were opposed to Zhuge Liang's Northern Expedition strategy, and Kong Ming chose to call himself sick and stay closed. Sima Yi, who got the news, realized that the opportunity had come, and offered advice to Cao Pi to use the Five Routes army to attack Shu. Liu Chan was terrified when he heard this, and could only ask Kong Ming for help in person.
Kong Ming put aside the grievances of the court and offered advice to stage the "Anjuping Five Roads" to prove the significance of the Northern Expedition. This is where the clash between two top minds begins, and history is irreversible. After the earth-shattering battle, Zhuge Liang failed to "go out of Qishan Mountain" and finally died of illness in Wuzhangyuan, drawing an end to the grievances of the old enemy. However, Sima Yi did not control the government. On the contrary, Cao Rui's superb way of employing people made Shuangcao feel suspicious of him, but he was able to control the balance between the two sides and make them reach a balance. Although Sima Yi was also restricted by Cao Zhen and others, the emperor gave him benefits from time to time and let him be safe. Soon after, Cao Xiu fell for Soochow's trick and lost 150,000 troops, and he himself was seriously wounded and died.
Cao Zhen fell for Kong Ming's strategy and died during Zhuge Liang's Northern Expedition, and since then Sima Yi has become an invincible existence in the court. But as fate would have it, Cao Rui lived a shorter life than his father, and died at the age of only 33. On his deathbed, he realized that there was no one in the court who was Sima Yi's opponent. In order to keep the Cao family, he decided to set up his youngest son Cao Fang as the emperor, appointed two auxiliary ministers to arbitrate major affairs in the court, and granted military power to Cao Zhen's son Cao Shuang. This decision had a huge impact on Sima Yi, although he had the right to intervene in the government, but he had no military power, just a hollowed out Taifu, and was threatened by Cao Shuang. Although he sent away the three generations of leaders of the Cao family, for Sima Yi, who was nearly sixty years old, there were not many opportunities left for him.
As Cao Shuang's threat became more and more serious, Sima Yi knew that he couldn't fight hard, so he simply didn't even go to court, preferring to be an idler with nothing to do, indulging in fishing and sword practice, and not asking about the world. Seeing him like this, Cao Shuang knew that he was at ease, and he also relaxed his vigilance against him. But Sima Yi is an ambitious old fox after all, he endured humiliation for ten years, just waiting for the opportunity, and finally the opportunity came. In 249 AD, taking advantage of Cao Shuang and the little emperor hunting, Sima Yi, who was already over seventy years old, quickly captured the court and armory with his trained retainers and dead soldiers, and launched the famous "Gaopingling Rebellion". At that time, Cao Shuang held military power and had the emperor by his side, so he had a great chance of winning. But Sima Yi expected that Cao Shuang had long been obsessed with drunken gold and no longer had the courage to draw his sword. So, in the end, he succeeded in removing this thorn in his eye.
It can be seen that although Sima Yi sent away three generations of the Cao family, Cao Rui's deathbed deployment prevented him from quickly occupying the court's ambitions. This obstacle lasted for a full decade, but Sima Yi's patience eventually triumphed, and the three kingdoms were finally unified under the Sima clan.